Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

If your delivery date matters at all, consider that Winston has had mysterious delays many months long reported on this forum from time to time. Whoever you contact, you might want to specifically ask if the cells you need are physically present, in stock, on the shelf, so that delivery can be guaranteed.

Yes, things can be air shipped from China. Yes, a slow boat from China still only needs a month. But no, neither of those solutions really is a reliable way to get your batteries, if you aren't planning to spend the whole winter in Miami. Or longer.

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

There had been several posts questioning fulfillment problems with at least one vendor, Balqon, who apparently are sole distributors in the US. I'm sure someone will pop up with some of the details on that. Possibly things have changed there by now, but IIRC there were some questions about why something new and in stock would turn out to be mismatched two year old production that took over three months to be shipped.

I think the conclusion that came out of that, is whoever you buy from, use a credit card, specify your order terms by email or fax so you have a copy of them, and if the batteries don't arrive on time and in good order (new, same batch numbering) you have the chance to refuse the order and charge back the purchase.

Of course, no one can really guess what will or won't be in stock five months from now, apparently the industry isn't that mature yet.

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Beware of the lithium conspiracy brigade :lol: Sinopoly and Winston use the same chemistry, it cost Sinopoly very big $$ to get it. CALB make great cells for electric vehicles, they can be discharged at a 5CA rate with a much better voltage sag than the Winston/Sinopoly cells, but their calendar cycle life is less due to the very thin deposit layers that enable this high rate discharge. Similar to lead acid start batteries compared to deep cycle batteries. The results are similar as well, the slow discharge rate associated with house battery use requires a cell construction with thicker active material to improve the long term cycle life and produce a constant voltage during the discharge cycle. Winston/Sinopoly will hold their voltage above 3v per cell all the way down to 100% use of the advertised capacity at a 0.5CA or less discharge rate and do this yr in/yr out, none of the other manufacturers have this ability.... yet. There will be a market swing to lithium house storage soon and LFP/LYP being the best/safest chemistry for this purpose mass manufacture of house battery rated cells will be the next big thing. No idea how long that will take to eventuate though.......

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I ordered my Liyuan 400AH cells from Mike over at Lithium Ion Storage.mike@lithiumstorage.comLiyuan 400AH 3.2 volt CellsI paid about $425/cell plus shippingI also bought the buss bars from him to tie them all together into one nice happy 12.8v bank.

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:

Originally Posted by Maine Sail

I find the biggest hurdle is forgetting & unlearning everything we learned with lead acid. Once you get comfortable with never needing to get back to 100% SOC, nor really wanting to, nor caring if you hoover between 20% SOC and 60% SOC for weeks on end, managing LFP is significantly easier than dealing with lead acid.

For us it is extremely simple, when the bank is full we turn off all charge sources. When the bank gets down to 30% SOC or lower we will take an opportunity to charge when it presents itself. Only on rare occasions have we needed to turn the charge sources back on at 50% SOC or so in order to go 4+ days on the hook with peace & quiet. We can always extend our time without noise by flipping solar back on but I have really been trying to cycle to 80% DOD, or as close to it, with each cycle to see if all the promises of LFP are actually true, they certainly seem to be. If I had done what I have done with LFP over the last 4 years, with lead acid, I would have been through 4 banks already.....

I think you NAILED it amigo!
I often have to stare at my SOC meter and Look at the Voltage and literally FORCE myself to not panic after coming from the T-105 wet acid world.

I'm on a little over a year now with my 400AH bank (Liyuan out of china) and I can't tell you how happy I am with these batteries. In fact I think it was about the best $2000 addition for the boat in terms of making living aboard more comfortable.

With our heavy solar (420W or 1320W depending on what I'm testing) we just rarely if ever have to run our generator for charging, so for me it is more of an issue of making sure I do not overcharge the bank.

I started out by setting all of my charge devices at 13.4v (solar, wind, battery charger- and don't use the alternator since we live aboard on a mooring) but over time I have tweaked the charge voltage up to 13.8V, so that is my current charge number.

With No HVC or LVC my system is a butt simple system with just individual cell monitoring and a SOC meter and I do have a buzzer for HVA and LVA, just in case I have my head in an orifice. It is not abnormal on sunny days for the bank to be sitting at 13.8v from 11AM to about 3-4PM if we don't have a heavy load that day and the solar is basically trying to charge them at my 13.8v set-point. But once the battery charges up to the 13.8v set-point, I see the same affect as I would in a wet acid battery when I set my solar controller at a float voltage of lets say 14.1v for example. The amperage just drops down to a trickle. [[YES I know you do not "float" LiFePO4 batteries, so calm down...I'm just using that term and example to describe how I am using the charge voltage as an easy way to limit the charge amperage (or should I say overcharge) of the battery.]]

So far I have a pretty much zero cell voltage drift (less than 0.01v) in 13 months of service every day for a live aboard boat. So I'm not seeing cell balancing as something I feel the need to pay for at this point. I do turn off solar frequently to take them down to a 10% SOC, but that is not typical, I just use the "set it and forget it" approach much like most cruisers would want to do.

Negatives....
Hmmm....I can't think of any to be honest at this point, besides getting over the old wet acid way of thinking....it is pretty hard to forget everything you learned and relearn something new....but it is pretty fun.

I'm pretty happy in not having spent the extra $$ and complexity of a BMS, cut out this and cut out that, but remember I runs with scissors, so don't take battery advice from me! I'm a full time live aboard and my office is my boat, so I'm here to monitor and keep watch over things. Maybe I would want the HVC and LVC if I was an absentee boater.

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I'm getting more and more serious about LFP batteries. Since I had already started completely redesigning and replacing my primary battery wiring (batteries, switches, busses, all big cables to inverter/charger, alternators, panels, etc.). As any of you who have done this knows, it is a big, and expensive, project. The PO had it redone but the design does not meet my idea of a suitable system.

So now I am looking at what it would mean to replace my 3 8D Lifeline AGMs with one LFP house battery. Right now I am thinking 400Ah would be plenty. I have 760watts of solar and a good controller. A 265A DC genset. A 100A main enginealternator. A 2500w/150A inverter/charger.

I have read everything on this site and everything else I can lay my hands on and am trying to assimilate it all. I think I would be fine with building a DIY BMS like the one described by Maine Sail on his website.

The issue I am grappling with now is the importance of putting in relay switches to protect the expensive LFP battery from extreme low or high voltages. Maine Sail suggests to install some large relay battery switches (like the Blue Sea 7700) and have them on both the input and output side of the battery, and, isolate the charging and using side of the wiring so you can turn the charging off if the voltages are too high and turn off the using side for low voltages. His BMS design would control the switches for hi/lo voltage.

First of all this adds an additional level of dependence on more complication. I like KISS. Having a BMS is a necessary evil but adding more on top of that is not something I really want to do. I like manual battery switches. I have tried to find real estate to even put in remote battery switches and there really aren't good choices right now, even starting afresh. I want to be able to get to them readily and to put one on both sides of the house batteries is one more than you usually find. I will use manual switches for paralleling and starting in any case.

Complications are to turn off the alternator fields for both the genset and the main engine alternators before switching the house charging side off, and, how to handle a combined inverter/charger which uses the same DC cables for both charging and inverting. I may be overthinking it but right now an elegant solution to this (if it needs one) hasn't occurred to me.

I would love to get your thoughts and wiring diagrams about how you have installed your LFP batteries. I suspect some/most of you have not put in a relay driven battery switch to turn off the charging side and are relying on your controllers to stop the charging. Yes/no?

Have any of you put a relay switch to cut off the outflows automatically from the batteries? I don't liveaboard right now so this might be a bigger issue in this case for me. I suspect this is not a likely scenario but things happen and the consequences are major.

Any ideas are welcome. And thanks to Third Day for your thoughts/solution for your boat.

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

exMaggieDrum, I have just finished installation of our LiFePO4 system and I can offer you and the community the design and schematics. It is very close to what you are searching for, I think.
It's quite a lot to explain and digest, though. I am planning to write several blog posts on this on our web site but I will need some time to document it thoroughly.
If you need some quick input I can post the schematics here and follow up with the blog posts later.